1. Field of the Invention
The present invention generally relates to a beam shaping module and, more particularly, to a beam shaping module capable of reversing the energy distribution pattern of one of a first beam and a second beam split by a beam splitter and capable of shaping and combining the first beam and the second beam.
2. Description of the Prior Art
Laser beam shaping has attracted lots of attention in industries, medical applications and academic researches. For example, laser beam shaping is widely used in applications, where the intensity distribution of laser is precisely controlled, such as photolithography in semiconductor processing, micro-circuit repair, micro-machining, cutting, welding, material growth, optical data storage, plastic surgery, nuclear fusion, etc.
Generally, the intensity distribution of a single-mode laser is spatially Gaussian. However, the intensity distributions of some multi-mode lasers are very complicated. In some applications, it is required that the intensity distribution of lasers is uniform with sharp corners, which leads to advancement in laser beam shaping.
The currently used methods in laser beam shaping use optical components such as lenses, diffraction elements, lens arrays, light pipes and combination thereof. Lenses and diffraction elements are only suitable for single-mode lasers. For multi-mode lasers, lens arrays or light pipes are required. There are advantages and disadvantages. For example, the non-spherical lenses for lens shaping are complicated in manufacturing and costly. The optical paths are precisely aligned; otherwise the laser intensity distribution will be changed. Issues in alignment appear for diffraction elements. Advanced diffraction elements are required to improve the efficiency, which leads to manufacture complexity and cost. When a single-mode light source is used with lens array, interference and diffraction sometimes happen to cause non-uniformity. If a light pipe is used, the transmission is reduced because the length and multi-reflections make downsizing and improvement in transmission harder.
In U.S. Pat. No. 4,793,694, two reflectors are used to split an incident light beam into three beams. Then, another two reflectors are used to make these three beams overlap on one plane to uniformize the irradiancy. In this embodiment, the reflectors have to be fine tuned to specific angles with additional wave plates to adjust the coherence of these three beams and prevent interference fringes from making the uniformity worse. In another embodiment of this disclosure, a single prism is used to split an incident light beam into three beams and make these three beams overlap on one plane to uniformize the irradiancy. However, no wave plates can be used to adjust the coherence of these three beams and prevent interference fringes from making the uniformity worse.
Therefore, there is need in providing a beam shaping module with an attempt to overcome the foregoing drawbacks.